JavaScript Strings

🔹 What are Strings in JavaScript?

A string in JavaScript is a sequence of characters used to represent text. Strings can contain letters, numbers, symbols, and spaces. They are enclosed in either single quotes (' '), double quotes (" "), or backticks ( ).

🔹 Creating Strings in JavaScript

let singleQuote = 'Hello, World!';
let doubleQuote = "JavaScript Strings!";
let templateLiteral = `This is a string using backticks.`;

💡 Backticks ( ) allow you to use template literals, which support multi-line strings and variable interpolation.

🔹 String Properties

length → Returns the length (number of characters) in a string.

let text = "Hello!";
console.log(text.length); // Output: 6

🔹 Common String Methods

1️⃣ Changing Case

toUpperCase() → Converts to uppercase
toLowerCase() → Converts to lowercase

let str = "JavaScript";
console.log(str.toUpperCase()); // "JAVASCRIPT"
console.log(str.toLowerCase()); // "javascript"

2️⃣ Extracting Parts of a String

slice(start, end) → Extracts a part of a string
substring(start, end) → Similar to slice, but cannot accept negative indexes

let text = "Hello, JavaScript!";
console.log(text.slice(7, 17)); // "JavaScript"
console.log(text.substring(7, 17)); // "JavaScript"

3️⃣ Searching in Strings

indexOf(value) → Returns the position of the first occurrence
lastIndexOf(value) → Returns the position of the last occurrence
includes(value) → Checks if a string contains a specific value (returns true or false)

let sentence = "Learn JavaScript at JavaScript Academy!";
console.log(sentence.indexOf("JavaScript")); // 6
console.log(sentence.lastIndexOf("JavaScript")); // 21
console.log(sentence.includes("Academy")); // true

4️⃣ Replacing Content

replace(oldValue, newValue) → Replaces the first occurrence of a value

let phrase = "I love JavaScript!";
console.log(phrase.replace("JavaScript", "Coding")); // "I love Coding!"

💡 Use replaceAll() to replace multiple occurrences.

🔹 String Concatenation (Joining Strings)

1️⃣ Using `+` Operator

let firstName = "John";
let lastName = "Doe";
console.log(firstName + " " + lastName); // "John Doe"

2️⃣ Using `concat()` Method

let text1 = "Hello";
let text2 = "World";
console.log(text1.concat(" ", text2)); // "Hello World"

3️⃣ Using Template Literals ( )

let name = "Alice";
let greeting = `Hello, ${name}! Welcome to JavaScript.`;
console.log(greeting); // "Hello, Alice! Welcome to JavaScript."

💡 Template literals allow inserting variables using ${}.

🔹 Conclusion

Strings store text and are enclosed in quotes (' ', " ", or ` `).
Use string methods to manipulate text: toUpperCase(), slice(), replace(), split(), etc.
Template literals (` `) allow variable interpolation and multi-line strings.
String properties like length help retrieve information about the string.

JAVASCRIPT